Weight Loss: Is exercise or diet more important?

If you’re planning on walking any extra weight off, you better prepare for a long trip. Exercise scientists estimate it will take you about 150km of walking to shed just one kilogram of fat, which is a long way to go for a measly kilo.

For a while now, what you eat has been considered more important than the exercise you do in the argument over which has more impact in losing weight.

That idea was upended last year, when scientists from the Global Energy Network claimed there was “virtually no compelling evidence” that fast food and sugary drinks are the causes of obesity.

Rather, they argued, a lack of activity is behind the world’s burgeoning waistlines. But after a backlash from health experts when it was revealed the Global Energy Network was funded primarily by soft-drink giant Coca-Cola, the network backed away from its original stance. They now say diet has a role in causing obesity, along with physical activity.

So where does that leave anyone hoping to drop a few kilos? Is all that walking to and from work a waste of time? Well, don’t throw your runners away just yet. Although relying on exercise alone is a hard way to lose weight, it still delivers health benefits that can’t be ignored.

The Banana Bread Effect

Dropping kilos is simple on paper – it’s an energy equation in which you either cut the kilojoules going in, or you increase them going out. Or you do a mixture of both.

Combining exercise and diet is definitely the best way to lose weight, because anything that shifts the balance towards a deficit of energy will help.

“The big misconception is, however, that I can lose a lot of weight by doing exercise,” University of Sydney exercise physiologist Nathan Johnson says.

Your good efforts to exercise can backfire if you feel hungrier afterwards or reward yourself with extra food. In other words, a typical half-hour workout session can be “blasted away” by one piece of post-session banana bread that goes down in a few minutes.

“We tend to compensate with our behaviours – we might treat ourselves or feel a bit hungrier,” Johnson says. “So those sorts of things can sabotage the potential positive effects of exercise in losing weight.”

A recent study on marathon runners underlines his point, with a Harvard University researcher in the US finding that most of the 64 charity runners he studied didn’t lose weight in the course of their training. In fact, only 11 per cent lost weight and several (mostly women) actually gained some over the three months of the four-day-a-week running program.

And in another study in the International Journal of Obesity, researchers discovered that women who walked regularly, but changed nothing else about their diet, did lose two kilos in a year – but it took about 155 hours of exercise to achieve that.

The Kitchen Workout

So if you’re looking to lose weight, you could be better off spending more time in the kitchen, prepping healthy meals and snacks to cut kilojoules than sweating it out in the gym.

“Exercise is really important for a variety of reasons, but it’s not the thing upon which you’re going to bring about weight loss,” associate professor Amanda Salis, a researcher at the University of Sydney’s Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders, says.

Salis studies the best ways to help people lose weight and says many of the participants she works with find it difficult to make a complete overhaul of their lifestyles.

So focus on one aspect of the weight equation first. “The effort you put into eating better and reducing kilojoule intake will give you a better outcome, in terms of losing weight, than exercising,” she says.

Once you’ve nailed the healthy eating, though, dig out those runners. A 2014 study in the US showed, over a 10-year period, those who were most successful in keeping the kilos off were people who exercised regularly, and also watched what they ate.

On The Double

Focusing on both your fitness and diet will help the weight come off quicker. “If you’re only at the stage where you’re fixing one of these areas at the moment, that’s better than nothing. But if you want the most bang for your buck, you’ve got to look at both things,” Sports Dietitians Australia spokesperson Simone Austin says.

“Obviously, diet is a hugely important factor for weight loss, but you’re going to get more results and feel better by doing exercise that suits you as well.”

Exercise will also increase your muscle mass, which is good news for a higher metabolic rate. “Muscle is the most ‘expensive’ tissue in the body – it actually takes more kilojoules to keep your muscle mass there than body fat,” Austin says.

“Having more muscle increases your resting metabolic rate, so exercise will have a longer-term impact by helping you have a greater muscle mass.”

Apart from making you stronger and fitter, exercise has a host of other health benefits, including helping to shift visceral fat around our abdomen and organs. University of Sydney researchers are finding exercise helps move this type of fat, even if the scales don’t want to budge.

“Anything that puts weight through our bones, such as walking or yoga, is going to help our bone density,” Austin says.

To offset the extra hunger you may feel after exercising, she suggests moving the timing of your eating rather than adding to it. Have an early lunch if you’re hungry after a walk, or add a side of salad or soup, rather than an additional sandwich or cake.

“We’ve got to think more of health than just weight,” Austin says. “Exercise is one of those combinations that will complement the healthy food you eat for weight as well as other conditions.”